Effect of Chemistry on the Transformation of Austenite to Martensite for Intercritically Austempered Ductile Iron

dc.contributor.author

Banerjee, Sayanti

en_US

dc.date.accessioned

2013-02-19T22:41:13Z

dc.date.available

2013-02-19T22:41:13Z

dc.date.issued

2013-01-11

en_US

dc.identifier.other

vt_gsexam:156

en_US

dc.identifier.uri

http://hdl.handle.net/10919/19258

dc.description.abstract

Intercritically austempered ductile iron (IADI) with a matrix microstructure of ferrite plus metastable austenite has an excellent combination of strength and toughness. The high strength and good ductility of this material is due to the transformation of metastable austenite to martensite during deformation. In the present study, the transformation of austenite to martensite for intercritically austempered ductile irons of varying alloy chemistry (varying amounts of nickel and/or manganese) were examined using in-situ neutron diffraction under strain-controlled loading at VULCAN at the Spallation Neutron Source at Oak Ridge National Laboratory (ORNL). Both diffraction and tensile data were collected and synced using the VDRIVE software (a proprietary ORNL software package). The single peak fit method was employed in the analysis of the diffraction data.

In this thesis, the stress and strain for the start of the transformation of metastable austenite to martensite were determined. The development of residual stresses during deformation and the elastic diffraction constants for both the ferrite and austenite phases were also determined. The material was characterized using optical microscopy, backscattered imaging in the scanning electron microscopy, energy dispersive spectroscopy and transmission electron microscopy.

en_US

dc.format.medium

ETD

en_US

dc.publisher

Virginia Tech

en_US

dc.rights

This Item is protected by copyright and/or related rights. Some uses of this Item may be deemed fair and permitted by law even without permission from the rights holder(s), or the rights holder(s) may have licensed the work for use under certain conditions. For other uses you need to obtain permission from the rights holder(s).

en_US

dc.subject

martensitic transformation

en_US

dc.subject

critical stress

en_US

dc.subject

neutron diffraction

en_US

dc.subject

ductile iron

en_US

dc.subject

intercritical heat treatment

en_US

dc.subject

lattice strain

en_US

dc.subject

di

en_US

dc.title

Effect of Chemistry on the Transformation of Austenite to Martensite for Intercritically Austempered Ductile Iron